Objectives: To evaluate the microtensile bond strength (MTBS) of self-etching adhesive systems to enamel and dentin surfaces following different modes of primer application. Methods: Flat enamel surfaces (bovine incisors) and flat dentin surfaces (human molars) were bonded with: Clearfil SE Bond (CSEB) and Etch & Prime 3.0 (EP). Adhesive systems were applied with and without agitation of the primer during application. Resin composite build-ups (6 mm in height) were constructed incrementally (1.5 mm) with Tetric Ceram. After 24 h storage in water at 37^oC, the bonded teeth were vertically sectioned into beams with cross-sectional areas of 1 mm². Beams were tested in tension in an Instron machine at 0.5 mm/min. Results were analyzed by ANOVA and Student t tests (p<0.05). Results: Mean (SD) MTBS values (MPa) for each subgroup (n=10) are shown in the table: letters show differences between with and without agitation groups, numbers show differences between adhesives. Conclusions:EPon enamel, and CSEB on dentin, showed the highest MTBS when the primer agitation technique was used.(CICYT/FEDER: MAT2001-2843-CO2. RED CYTED VIII.J).

	Enamel	Enamel	Dentin	Dentin
	Without agitation	With agitation	Without agitation	With agitation
CSEB	22.10 (10.7) 1a	12.18 (2.5)   1b	44.03 (12.2)   1A	54.78 (9.6)  1B
EP	25.7 (9.8)     1a	28.91 (4.9)   2a	11.80 (2.2)     2A	18.99(6.7)   2B